SPECIFICATION FOR THE DESIGN OF - Transcon Steel

Commentary on the Prescriptive Method for One and Two Family Dwellings - 2004 39
D. FLOOR FRAMING DESIGN EXAMPLES
D1 Floor Joist Design
Calculate the allowable span for a 1000S162-54 single span joist spaced at 24” on center,
supporting a live load of 40 psf plus a dead load of 10 psf, using the provisions of the AISI
Specification (AISI, 1999). The compression flange of the joist is laterally restrained with the
application of floor sheathing.
D1.1 Shear Capacity
Using the AISIWIN (Version 4.0) computer program, the nominal shear capacity is 2,408
lb for a joist with no holes. (AISIWIN is available from DEVCO Software, Inc., Corvallis,
OR.). The above shear capacity is verified below using Section C3.2 of the Specification.
a = 2.5” (hole depth across web)
Non-circular holes – 4” long
F y = 33 ksi
b = 24” (hole spacing)
t = 0.0566” (thickness)
R = 0.108” (inside bend radius)
h = 10 - 2(0.0566 + 0.108) = 9.671”
h/t = 9.671 / 0.0566 = 170.87 < 200
ok
Ek
v
0 .96 =
F
y
0.96
29,500x5.34
33
= 66.33
Ek
v
1 .415 =
F
y
1.415
29,500x5.34
33
= 97.76
where k v = 5.34 for unreinforced webs
Ekv
h/t = 170.87 > 1 .415 V n = 0.905 Ek v t 3 /h
F
V n =
3
0.905(29,500,000)(5.34)(0.0566)
9.671
y
= 2,673 lb (web with no holes)
Φ v V n = 2,673 x 0.90 = 2,406 lbs
(web with no holes)
Calculate the reduction in the nominal shear capacity due to the presence of punchouts
using Section C3.2.2 of the AISI Specification.
Check applicability of Section C3.2.2:
d 0 /h = 2.5/9.67 = 0.258 < 0.7 ok
h/t = 170.87 < 200 ok
Holes centered at mid-depth of the web ok
Clear distance between holes ≥ 18” ok
Circular hole diameter ≤ 6” ok
Non-circular holes, hole depth (d 0 ) = 2.5” ≤ 2.5” and b = 4” ≤ 4.5”
ok